Enterprise since its last, 1995(?)RCOH could go quite a while...supposedly a 22 year extension of life. Supposed to be retired 2013, and be replaced by CVN-78. We'll see.
It is likely that the Administration WANTS the Navy fleet of carriers to go down to 9 ships. Their old plans had Kitty Hawk to be decommissioned in 2008...I believe to be replaced ultimately by CVN-77.
They have also commissioned a study to justify a 9 ship carrier fleet... Have to see if I can dig that up.
The reactor may last that long but the other equipment? There's 4 air craft elevators, 6? electrical generators, the turbines, Thrust block, catapults, arresting gears, etc that may not hold up to it.
Nukes like the conventionals in the KITTY HAWK and JFK class are still steam driven. The difference is how the steam is generated. This means a 1200 PSI super heated steam piping system. One leak the size of a number 2 pencil lead can dismember or decapitate you and you will never know the leak is there. This is why it did not make one bit of sense to give the older carriers Ship Life Extension Program S.L.E.P. and not the newer ones. They ran the America till it blew up at Norfolk then ran it another cruise. The JFK is in as bad if not worse shape than AMERICA was. These two were younger than Enterprise. I think the administration like the DEM's is steering us into a multinational reliance defense posture. That IMO is not good at all. For any leader of this nation from any party or branch of government to place our national defense into such a position that we are completely alliance dependent which is where this is head I call it Tyranny.